¥ 
£. A. Hill—Notes on Argon and Helium otD 
unknown gas in the gases of certain mineral springs in the 
Pyrenees mountains (Nature, Sept. 12, 1895, p, 487). The 
question raised as to the presence in cleveite gas of helium, 
the element giving the solar line D*, has now been fully set- 
tled, the line being double both in solar and terrestrial helium. 
A good account of this question and its solution will be found 
in the Observatory for Aug. 1895, p. 295. 
The work of Runge and Paschen upon the spectrum of 
cleveite gas subdivides the lines into two series, each of which 
in all probability stands for a different gas or class of gases. 
They also note certain rythmical relations between the wave 
lengths and those of hydrogen lines, and note a marked simi- 
larity in type between the helium lines and those of the spec- 
tra of the alkali metals. (Philosophical Magazine, Sept. 1895, 
eT 
7 We ee finally to the work of Mr. Crookes on the helium 
spectrum published in the last issue of the Journal, which 
may be summarized as follows, the grouping being my own: 
« 
HELIUM LINES OBSERVED BY WM. Crookus, F.R.S., ETC. 
> 
Intensities. | Occurrence in 
| , 
3 Whee Fa | Hi z 
+ : | od oO 
wes si¢i ie eebhi| NN 
Bese |) sa, s | | s = S 2 g 
5 ecm | a o | A = a0 a0 ‘= 
= fo) os} a > = 2 32) ro) = 
Se | = ee i a =) oO 4 fa a8) 
A 16); 30 4 | 9:2 strong strong strong strong | strong 
ap 33 2|| 10 6 | 8 strong strong strong | strong 
C 2) ea iver’ faint strong strong | strong 
D Myer o: | 10: | 10 very faint |very faint strong | strong 
EK | Rl ae strong strong strong | strong 
F 1} 10 | 10 | 10 strong strong strong 
G 1]; 5 5 | 5 strong strong | strong 
H ai. 9 eo prominent |very faint’ very faint 
h m8 Saleas prominent very faint|/very faint 
I 2|| 10 a) 9°d strong strong 
J 1}; 8 SFiS ; strong | strong 
K lj} 4; 4] 4 strong strong 
L 1\| 10 | 10 | 10 ||very strongivery faint 
Mey 21-10 | 3 | 7°08 strong 
Maple 9 | 2) 633 strong 
Total\ 71 11 8 ea 8 9 10 
Blank spaces indicate the absence of lines and the table does 
not include a number of lines for which Crookes in his table 
gives no data, as for instance 4931-9 intensity 3, 4544-1 int. 5, 
